The Right Light at Night

King Alfred’s Tower: Paul Howell (@PictorImages)

30 April 2023

In October 2019, Cranborne Chase AONB became only the 14th International Dark Sky Reserve (IDSR) worldwide (there are now only 21). This prestigious status was awarded in recognition of the exceptional character of our dark skies in particular, and our nocturnal environment in general.

We need artificial light at night for safety, for work, and for leisure, but this conflicts with nature’s need for the night that has shaped millions of years of evolution. Our challenge is to balance our needs and those of the nocturnal environment, so how can we achieve this? The principles of responsible outdoor lighting are encapsulated in the mantra Right Light, Right Place, Right Time.

The last two of these are obvious. Right Place is simply to use careful aiming and shielding to direct the light to where it is needed and ensure that it does not intrude where it is neither wanted nor needed, especially upward into the sky. Right Time is when it will actually be useful, and this can be achieved by using timers or PIR motion detectors. On-all-night security lighting often merely acts as a beacon to advertise that there is something valuable nearby.

The Right Light is a softer “warm white” light of the minimum necessary brightness, which creates neither glare nor dark shadows that conceal what the light should reveal.

If you drive, you will have noticed that you need to wipe far fewer insects off your windscreen than even 5 years ago. This phenomenon reveals the long-term effects of the wrong sort of light: harsh, cold, bright white “blue rich” light. This has been devastating for nocturnal wildlife: amongst other harms, it is a direct driver of the “insectageddon” component of the biodiversity collapse. In the UK, having already lost more than 60% of our insect populations in the last 30 years, we are on course to lose 40% of what remains in the next 30. This is simply not sustainable and, of the major drivers of this decline, artificial light at night is the easiest to remedy.

Blue-rich Insects: International Dark Sky Association

It seems that wherever we look at the natural world, from migrating birds to mating frogs, from foraging mammals to plankton, from sea turtles to bats, it is adversely affected. But it’s not only wildlife: the American Medical Association has already declared light pollution to be a human health risk because of its harmful effects on us, primarily through melatonin suppression and the disruption of our circadian rhythms.

So what you can do? In the spirit of Think Globally, Act Locally, you could start by using this handy flowchart to check if your own outside lighting is dark sky friendly: https://tinyurl.com/2pbny5dv

In Cranborne Chase AONB we offer advice and funding to support the movement towards Dark Night Sky friendly light fittings, not only domestically, but also for farmers and land managers through the Farming in Protected Landscapes programme. Even if you live outside our area, we can usually offer advice and/or put you in touch with a responsible lighting advocate nearer to home.

Ends

For more information or advice, you can contact The IDSR’s Dark Skies Adviser, Steve Tonkin, at stevetonkin@cranbornechase.org.uk .